Oxygen Saturation in Therapy Blood Sample (PaO₂ measurement)
This test measures the amount of oxygen dissolved in your blood, specifically the partial pressure of oxygen (PaO₂), which reflects how well your lungs are delivering oxygen to your bloodstream. It’s often used in therapy settings to assess respiratory function.
["This test helps doctors monitor how well your lungs are working to deliver oxygen to your body during treatment or recovery."]
Key facts at a glance
- LOINC
- 55415-4
- Short code
- SaO2 & therapy Pnl
- Synonyms
- SaO2 & therapy Pnl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What This Test Measures
PaO₂ measures the pressure of oxygen in your arterial blood, expressed in millimeters of mercury (mmHg). It’s a critical indicator of oxygenation status, often used alongside other tests like oxygen saturation (SpO₂) to evaluate lung function and potential breathing issues.
Why It’s Done in Therapy
In therapy settings, PaO₂ testing is commonly performed to monitor patients with respiratory conditions (e.g., chronic obstructive pulmonary disease, pneumonia, or those on ventilators). It helps track how well oxygen is being absorbed into the blood and whether adjustments to treatment (like oxygen therapy) are needed.
How the Test Works
Blood is drawn from an artery (often in the wrist or arm) and analyzed in a lab. The test measures the partial pressure of oxygen in the arterial blood, which is different from oxygen saturation (SpO₂), which is measured in finger or ear blood vessels and reflects overall oxygen-carrying capacity.
What the Results Mean
Results are compared to standard ranges for healthy individuals, though exact values can vary by lab and patient condition. Low PaO₂ levels may indicate poor lung function, reduced oxygen delivery, or other respiratory problems, while high levels might suggest conditions like polycythemia (increased red blood cells).
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
PaO₂ is a key indicator in diagnosing and managing respiratory disorders. Low values can signal conditions like severe asthma, lung infections, or heart failure, prompting immediate medical attention. In therapy, it guides decisions about oxygen therapy, ventilation support, or adjustments to medications to improve oxygenation.
Short name
PaO₂ (Partial Pressure of Oxygen)
Frequently asked questions
How often is this test done during therapy?
What does a normal PaO₂ level feel like?
Can I prepare for this test at home?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy